1. Field of the Invention
The invention relates to a method of limiting the quality of service of data transmission in a wireless telecommunications system which comprises at least one terminal and a fixed network which comprises a database for storing subscriber data, the method comprising defining the quality of service of data transmission by means of quality of service parameters.
The invention also relates to a wireless telecommunications system which comprises at least one terminal and a fixed network which comprises a database for storing subscriber data by means of quality of service parameters, the quality of service being defined by means of quality of service parameters in the system.
2. Description of Related Art
In addition to speech services, digital mobile communication systems offer different data services, such as data transmission services and e-mail and Internet connections. Various multi-media services which are used via the mobile communication network are being introduced gradually. Different data services set different requirements on the data transmission connection needed. Successful file transfer, for example, does not set any special requirements on the bit rate or delay of the transmission connection used, whereas real-time video transmission requires a high bit rate as well as minimal delay and number of errors to function properly. To allocate the limited resources of the mobile network optimally to mobile subscribers utilizing various services, special data transmission methods which allow control of the properties of a data transmission connection have been developed for mobile communication networks.
Both circuit-switched and packet-switched data transmission methods have been developed for the European digital GSM mobile communication network (Global System for Mobile Communication), for example. During the past few years the European Telecommunication Standards Institute ETSI has drawn up standards for the GSM 2+ phase which also define a new packet-switched data transmission service known as the GPRS (General Packet Radio Service). The GPRS is a packet network which utilizes the GSM network and in which transmission of data packets on the air interface between the mobile station and the GPRS network is optimized by means of GPRS protocol layers. The network operator and the mobile subscriber can agree on the data rate to be used within a range of 9.6 to 171.2 kbps. The GPRS standards also define quality of service parameters, i.e. QoS parameters, which, in addition to the above-mentioned data rate, include priority between the services, reliability of data transmission (i.e. error ratio) and allowed delay. By controlling these QoS parameters a suitable QoS profile can be selected for each data connection and service to be used. When the mobile user wants to use a certain data service, he may ask for a QoS profile suitable for this data service from the network operator in connection with call set-up. If the mobile communication network can carry out the request made, the network allocates a connection having the desired QoS profile to the mobile station. If the network is unable to allocate a connection which is good enough for the requested QoS profile e.g. because there are not enough resources available, the mobile station has to ask for a connection with a lower QoS profile or wait until a sufficient amount of the network resources becomes available for carrying out the original request. In that case the network operator may charge the mobile subscriber on the basis of the QoS profile used, and naturally, the use of a transmission connection with a better quality costs more than the use of a connection with QoS parameters of a poorer quality.
A problem arises in the arrangement described above when the mobile user and the owner of the mobile subscription (i.e. the one who pays the bill) are different persons. For example, an employee may have a company mobile phone, or parents may pay their children's mobile phone bills. When various data services become differentiated, efficient use of the available services will require transmission connections of very different qualities. The unit prices of these connections also vary considerably. In that case it might be in the interests of the owner of the mobile subscription to limit the costs of the transmission connections to be used to a certain unit price. This is not, however, possible in the existing GPRS system where the mobile user makes a request for the desired quality of the transmission connection to the network and the owner of the mobile subscription cannot influence this in any way. We also face similar problems in other mobile network-based network solutions where the quality parameters of a transmission connection can be changed as desired. These networks include the GSM-based high-speed circuit-switched data service HSCSD and intelligent network solutions IN designed for mobile communication networks.